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Neha says: "Pipe A fills a tank in 4 h and pipe B in 6 h, so together they need $\frac{4 + 6}{2} = 5$ h." What is the correct time?

Competition practicePipes & Cisterns

A2 h
B2.4 h
C5 h
D10 h

Step-by-Step Solution

Add rates, not times:

\frac{1}{4} + \frac{1}{6} = \frac{5}{12}

→

\frac{12}{5} = 2.4

h. Two pipes together must be faster than the faster pipe alone.

Answer: B) 2.4 h

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